Ah I was going to say what he said, try plugging in the speakers and using them and then unplug them maby the system thinks that externals are still plugged in, and try all volume related buttons and switches. Maby restart it lol. I think u can do a hardware check using the re instal disc, but not sure if it checks speakers (I think it should). If all else fails the old fashion way is always helpfull try hitting it lol dont do that😀.